[AlCp2](+): Structure, Properties and Isobutene Polymerization

Reaction of the protonic ether compound [H(OEt2)(2)]-[Al(ORF)(4)] (R-F = C(CF3)(3)) with AlCp3 leads to the formation of the [AlCp2](+)-cation, which is stabilized by the weakly coordinating [Al(ORF)(4)](-) ion. Besides [AlCp2](+), the ion [AlCp2 center dot 2Et(2)O](+), which is stabilized by two ether Molecules, is formed in an equilibrium reaction. The so far unknown molecular structure of [AlCp2](+) and the molecular structure of [AlCp2 center dot 2Et(2)O](+) are presented in this work. To get insight in the formation and the equilibrium between these two cations, quantum mechanical calculations were performed. Moreover, the influence of counterions like [Al(ORF)(4)](-) and [MeB(C6F5)(3)](-) on the activity of [AlCp2](+) to act as a polymerization initiating agent for isobutene was investigated.